Pca Exlinea Peptide Smoothing Serum 1Oz (29.5Ml)PCA ExLinea Peptide Smoothing Serum 1 oz (29. 5 ml) The PCA ExLinea Peptide Smoothing Serum is a high performance anti aging treatment designed to visibly reduce expression lines, smooth skin texture, and support a firmer, more youthful looking complexion. Developed by PCA Skin, a professional grade skincare brand used in dermatology clinics, this serum targets fine lines caused by repeated facial movements such as smiling, frowning, and squinting.